Post-Biginelli Ugi reaction towards synthesis of novel bisamides of dihydropyrimidinones: Substrate scope, modification and mechanism

A Biginelli, hydrolysis and Ugi four component reaction sequence was developed for the synthesis of novel dihydropyrimidinone (DHPM) bisamides in which an unprecedented but moderate 1,6 asymmetric induction was observed for this compound class. A detailed study is carried out to understand effects of various substitutions on the diastereoselectivity. Steric congestion led to sluggish Mumm rearrangement in some examples allowing the trapping of imidate intermediate by methanol. This unprecedented trapping confirms that slow Mumm rearrangement can lead to side products formation in Ugi reaction. [Display omitted]